The present invention relates to electrical moisture testers for measuring the moisture content of corn kernels on an ear of corn (i.e., "ear corn").
Electrical moisture testers for measuring the moisture content of vegetable matter, and in particular grains, are well known in the art. Most moisture testers operate on the principal that the electrical properties (namely, resistance or resistivity) of vegetable matter vary with the moisture content of the matter.
Some moisture testers, especially those for measuring grains, are designed to take bulk measurements after the grain or other crop has been harvested and is in storage. Such devices are not as reliable with corn if they do not penetrate the kernel since the resistance of the pericarp of a corn kernel is not considered a reliable indicator of the moisture content of the corn.
Moreover, bulk measuring devices which require separation of the kernel from the plant may not be useful or convenient in helping a farmer determine when to harvest the crop, or a seed corn company in determining "dry down" time of a new hybrid seed under development.
A moisture tester designed to estimate the moisture content of corn kernels on the cob is disclosed in an article entitled An Electronic Probe For Estimating Ear Moisture Content of Maize (Kang, et al, Crop Science, Vol. 18, November-December 1978, pp. 1083-1084). That device uses a pair of spaced needle-shaped conductors which are applied to penetrate the husk, kernels and cob. The moisture meter then signals the relative magnitude of the electrical resistance of the cob, kernels and husk in contact with the needle conductors.
It is known that the relationship between cob moisture and the moisture content of corn kernels on the cob, varies substantially with different corn genotypes, different moisture levels, and even with the weather. Thus, cob moisture can not be generally correlated with corn kernel moisture. It is also known that the moisture content of the husk can influence the value of the moisture reading obtained, especially when a test is being made in the field while the ear is still on the plant.